import logging
import sys
from contextlib import contextmanager
from typing import Generator

from sqlalchemy import create_engine, text
from sqlalchemy.orm import sessionmaker, Session
from sqlalchemy.exc import SQLAlchemyError

from app.config import (
    DATABASE_URL,
    LOG_LEVEL,
    LOG_FORMAT,
)

# =============================================================================
# LOGGING CONFIGURATION
# =============================================================================

logging.basicConfig(
    level=getattr(logging, LOG_LEVEL.upper(), logging.INFO),
    format=LOG_FORMAT,
    handlers=[
        logging.StreamHandler(sys.stdout),
    ]
)
logger = logging.getLogger(__name__)

# =============================================================================
# DATABASE SETUP
# =============================================================================

# Create SQLAlchemy engine with connection pooling
engine = create_engine(
    DATABASE_URL,
    pool_pre_ping=True,  # Verify connections before use
    pool_size=5,
    max_overflow=10,
    echo=False,  # Set to True for SQL debugging
)

# Session factory
SessionLocal = sessionmaker(
    autocommit=False,
    autoflush=False,
    bind=engine,
)


def get_db() -> Generator[Session, None, None]:
    """
    Dependency that provides a database session.

    Yields a SQLAlchemy session and ensures proper cleanup.
    """
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


@contextmanager
def get_db_session() -> Generator[Session, None, None]:
    """
    Context manager for database sessions (non-dependency use).
    """
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def check_db_connection() -> bool:
    """
    Test database connectivity.

    Returns:
        True if database is reachable, False otherwise
    """
    try:
        with get_db_session() as db:
            db.execute(text("SELECT 1"))
        return True
    except SQLAlchemyError as e:
        logger.error(f"Database connection failed: {e}")
        return False